Cooling apparatus with discrete cold plates disposed between a module enclosure and electronics components to be cooled

ABSTRACT

Cooling apparatuses and methods are provided for cooling an assembly including a substrate supporting multiple electronics components. The cooling apparatus includes: multiple discrete cold plates, each having a coolant inlet, a coolant outlet and at least one coolant chamber disposed therebetween; and multiple coolant-carrying tubes, each tube extending from a respective cold plate and being in fluid communication with the coolant inlet or outlet of the cold plate. An enclosure is provided having a perimeter region which engages the substrate to form a cavity with the electronics components and cold plates being disposed within the cavity. The enclosure is configured with multiple bores, each bore being sized and located to receive a respective coolant-carrying tube of the tubes extending from the cold plates. Further, the enclosure is configured with a manifold in fluid communication with the tubes for distributing coolant in parallel to the cold plates.

CROSS-REFERENCE TO RELATED PATENTS/APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 11/871,334, filed Oct. 12, 2007, and published Feb. 7, 2008 asU.S. Patent Publication No. US-2008-0030953 A1, entitled “CoolingApparatus and Method Employing Discrete Cold Plates Disposed Between aModule Enclosure and Electronics Components to be Cooled”, by Campbellet al., which is a continuation of U.S. patent application Ser. No.11/258,314, filed Oct. 25, 2005, which issued as U.S. Letters Patent No.7,298,617 B2, on Nov. 20, 2007, the entirety of each of which is herebyincorporated herein by reference in its entirety. This application alsocontains subject matter which is related to the subject matter of thefollowing applications, which are assigned to the same assignee as thisapplication and which are hereby incorporated herein by reference intheir entirety:

-   -   “Cooling System and Method Employing a Closed Loop Coolant Path        and Micro-Scaled Cooling Structure within an Electronics        Subsystem of an Electronics Rack”, Campbell et al., Ser. No.        11/008,771, filed Dec. 9, 2004; and    -   “Cooling Apparatuses and Methods Employing Discrete Cold Plates        Compliantly Coupled Between a Common Manifold and Electronics        Components of an Assembly to be Cooled,” Campbell et al., Ser.        No. 11/258,316, filed Oct. 25, 2005, and published Apr. 26,        2007, as a U.S. Patent Publication No. US-2007-0091570 A1.

TECHNICAL FIELD

The present invention relates to cooling apparatuses and methods forremoving heat generated by electronics components (e.g., devices,modules, systems, etc.) and to methods of constructing such coolingapparatuses. More particularly, the present invention relates to coolingapparatuses and methods for extracting heat from heat generatingelectronics components of a multi-component electronics module.

BACKGROUND OF THE INVENTION

As is known, operating electronic devices produce heat. This heat shouldbe removed from the devices in order to maintain device junctiontemperatures within desirable limits. Failure to remove the heat thusproduced results in increased device temperatures, potentially leadingto thermal runaway conditions. Several trends in the electronicsindustry have combined to increase the importance of thermal management,including heat removal for electronics devices, including technologieswhere thermal management has traditionally been less of a concern, suchas CMOS. In particular, the need for faster and more densely packedcircuits has had a direct impact on the importance of thermalmanagement. First, power dissipation, and therefore heat production,increases as device operating frequencies increase. Second, increasedoperating frequencies may be possible at lower device junctiontemperatures. Further, as more and more devices are packed onto a singlechip, power density (Watts/cm²) increases, resulting in the need toremove more power from a given size chip or module. These trends havecombined to create applications where it is no longer desirable toremove heat from modern devices solely by traditional air coolingmethods, such as by using traditional air cooled heat sinks. Thesetrends are likely to continue, furthering the need for alternatives totraditional air cooling methods.

One approach to avoiding the limitations of traditional air cooling isto use a cooling liquid. As is known, different liquids providedifferent cooling capabilities. In particular, liquids such asrefrigerants or other dielectric fluids (e.g., fluorocarbon fluid)exhibit relatively poor thermal conductivity and specific heatproperties, i.e., when compared to liquids such as water or otheraqueous fluids. Dielectric liquids have an advantage, however, in thatthey may be placed in direct physical contact with electronic devicesand interconnects without adverse affects such as corrosion orelectrical short circuits. For example, U.S. Pat. No. 6,052,284,entitled “Printed Circuit Board with Electronic Devices MountedThereon”, describes an apparatus in which a dielectric liquid flows overand around several operating electronic devices, thereby removing heatfrom the devices. Similar approaches are disclosed in U.S. Pat. No.5,655,290, entitled “Method for Making a Three-Dimensional MultichipModule” and U.S. Pat. No. 4,888,663, entitled “Cooling System forElectronic Assembly”.

Other cooling liquids, such as water or other aqueous liquids, exhibitsuperior thermal conductivity and specific heat compared to dielectricliquids. Water-based coolants, however, must be kept from physicalcontact with electronic devices and interconnects, since corrosion andelectrical short circuit problems are likely to result from suchcontact. Various methods have been disclosed for using water-basedcoolants, while providing physical separation between the coolant andthe electronic devices. For example, U.S. Pat. No. 4,531,146, entitled“Apparatus for Cooling High-Density Integrated Circuit Packages”,discloses the use of a conductive foil barrier; U.S. Pat. No. 4,879,629,entitled “Liquid Cooled Multi-chip Integrated Circuit ModuleIncorporating A Seamless Compliant Member for Leakproof Operation”, andIBM Technical Disclosure Bulletin Vol. 20, No. 2, July 1977, entitled“Liquid Cooled Module with Compliant Membrane”, disclose the use of aflexible barrier with thermal conduction enhancements (thermal studs andheatsinks, respectively); and U.S. Pat. No. 4,381,032, entitled“Apparatus for Cooling High-Density Integrated Circuit Packages”, andU.S. Pat. No. 5,294,830, entitled “Apparatus for Indirect ImpingementCooling of Integrated Circuit Chips”, disclose the use of flexiblebarriers, where pistons are used to maintain contact between the barrierand the devices to be cooled.

Notwithstanding the above, there remains a large and significant need toprovide further useful cooling apparatus enhancements for facilitatingcooling of electronic modules, and particularly multi-chip modules.

SUMMARY OF THE INVENTION

The shortcomings of the prior art are overcome and additional advantagesare provided through the provision of a cooling apparatus forfacilitating cooling of an electronics assembly comprising a substratesupporting multiple heat generating electronics components. The coolingapparatus includes: multiple discrete cold plates and a plurality ofcoolant-carrying tubes. Each cold plate has a first surface configuredto couple to a respective electronics component of the multipleelectronics components, and each cold plate is a coolant-cooled coldplate having a coolant inlet and a coolant outlet with at least onecoolant chamber disposed between the coolant inlet and the coolantoutlet. Each cold plate has at least two coolant-carrying tubesextending from a second surface thereof. Each coolant-carrying tube isin fluid communication with either the coolant inlet or the coolantoutlet of the associated cold plate from which it extends. The coolingapparatus further includes an enclosure having a perimeter region forengaging the substrate to form an at least partially enclosed cavitywith the multiple heat generating electronics components and themultiple cold plates being disposed within the cavity defined by thesubstrate and the enclosure. The enclosure is configured with aplurality of bores, each bore being sized and located to at leastpartially receive a respective coolant-carrying tube extending from oneof the cold plates. The enclosure is further configured with a manifoldin fluid communication with the plurality of bores and the plurality ofcoolant-carrying tubes disposed therein for distributing coolant inparallel to at least some cold plates of the multiple cold plates via afirst set of coolant-carrying tubes in fluid communication with thecoolant inlets of the cold plates, and for receiving coolant from atleast some cold plates of the multiple cold plates via a second set ofcoolant-carrying tubes in fluid communication with the coolant outletsof the cold plates.

In another aspect, a cooled electronics module is provided whichincludes an electronics assembly having a substrate supporting multipleheat generating electronics components to be cooled, and a coolingapparatus for facilitating cooling of the electronics components. Thecooling apparatus includes: multiple discrete cold plates and aplurality of coolant-carrying tubes. Each cold plate has a first surfaceconfigured to couple to a respective electronics component of themultiple electronics components, and each cold plate is a coolant-cooledcold plate having a coolant inlet and a coolant outlet with at least onecoolant chamber disposed between the coolant inlet and the coolantoutlet. Each cold plate has at least two coolant-carrying tubesextending from a second surface thereof. Each coolant-carrying tube isin fluid communication with either the coolant inlet or the coolantoutlet of the associated cold plate from which it extends. The coolingapparatus further includes an enclosure having a perimeter regionengaging the substrate to form an at least partially enclosed cavitywith the multiple heat generating electronics components and themultiple cold plates being disposed within the cavity defined by thesubstrate and the enclosure. The enclosure is configured with aplurality of bores, each bore being sized and located to at leastpartially receive a respective coolant-carrying tube extending from oneof the cold plates. The enclosure is further configured with a manifoldin fluid communication with the plurality of bores and the plurality ofcoolant-carrying tubes disposed therein for distributing coolant inparallel to at least some cold plates of the multiple cold plates via afirst set of coolant-carrying tubes in fluid communication with thecoolant inlets of the cold plates, and for receiving coolant from atleast some cold plates of the multiple cold plates via a second set ofcoolant-carrying tubes in fluid communication with the coolant outletsof the cold plates.

In a further aspect, a method of fabricating a cooling apparatus isprovided for facilitating cooling of an electronics assembly comprisinga substrate supporting multiple heat generating electronics componentsto be cooled. The method includes: providing multiple discrete coldplates with a plurality of coolant-carrying tubes extending therefrom,each cold plate having a first surface configured to couple to arespective electronics component of the multiple electronics components,and each cold plate being a coolant-cooled cold plate configured with acoolant inlet and a coolant outlet with at least one coolant chamberdisposed between the coolant inlet and the coolant outlet, each coldplate further having at least two coolant-carrying tubes of theplurality of coolant-carrying tubes extending from a second surfacethereof, each coolant-carrying tube being in fluid communication withone of the coolant inlet and the coolant outlet of the cold plate fromwhich the coolant-carrying tube extends; coupling each cold plate to arespective electronics component of the multiple electronics components;and providing an enclosure having a perimeter region, and engaging theperimeter region of the enclosure with a substrate to form an at leastpartially enclosed cavity with the multiple heat generating electronicscomponents and the multiple cold plates being disposed within the cavitydefined by the substrate and the enclosure, wherein the enclosure isconfigured with a plurality of bores, each bore being sized and locatedto at least partially receive a respective coolant-carrying tube of theplurality of coolant-carrying tubes extending from the cold plates asthe enclosure engages the substrate, the enclosure further beingconfigured with a manifold in fluid communication with the plurality ofbores and the plurality of coolant-carrying tubes disposed therein fordistributing coolant in parallel to at least some cold plates of themultiple cold plates via a first set of coolant-carrying tubes in fluidcommunication with the coolant inlets of the multiple cold plates, andfor receiving coolant from at least some cold plates of the multiplecold plates via a second set of coolant-carrying tubes in fluidcommunication with the coolant outlets of the multiple cold plates.

Further, additional features and advantages are realized through thetechniques of the present invention. Other embodiments and aspects ofthe invention are described in detail herein and are considered a partof the claimed invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter which is regarded as the invention is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other objects, features, andadvantages of the invention are apparent from the following detaileddescription taken in conjunction with the accompanying drawings inwhich:

FIG. 1A is a cross-sectional elevational view of one embodiment of acooled electronics module (taken along line 1A-1A of FIG. 1B), with acooling apparatus in accordance with an aspect of the present invention;

FIG. 1B is a cross-sectional plan view of the cooled electronics moduleof FIG. 1A taken along line 1B-1B, in accordance with an aspect of thepresent invention;

FIG. 2 is a top plan view of one embodiment of a cold plate employed ina cooling apparatus, in accordance with an aspect of the presentinvention;

FIG. 3 is a cross-sectional elevational view of an another embodiment ofa cooled electronics module with a cooling apparatus in accordance withan aspect of the present invention;

FIG. 4A is a cross-sectional elevational view of still anotherembodiment of a cooled electronics module (taken along line 4A-4A ofFIG. 4B), with a cooling apparatus in accordance with an aspect of thepresent invention; and

FIG. 4B is a cross-sectional plan view of the cooled electronics moduleof FIG. 4A taken along line 4B-4B, in accordance with an aspect of thepresent invention.

BEST MODE FOR CARRYING OUT THE INVENTION

As used herein, “heat generating electronics component” may comprise anycomponent of a computer system or other electronic system requiringcooling, and includes one or more integrated circuit devices,semiconductor chips, or other electronic circuitry requiring cooling.The “surface to be cooled” refers to a surface of the heat generatingelectronics component itself, or to an exposed surface of a thermalspreader, passivation layer, or other surface in thermal contact withthe electronics component, and through which heat generated by theelectronics component is to be extracted. A “micro-scaled coolingstructure” means a cooling structure or cold plate with a characteristicdimension of 200 microns or less. A “biasing mechanism” refers to anybiasing structure, such as one or more springs, leafs, etc., with asingle spring arrangement per cold plate being illustrated in oneembodiment provided herein by way of example only.

One example of coolant for a cooling apparatus in accordance with anaspect of the present invention is water. However, the conceptsdisclosed herein are readily adapted for use with other types of liquidcoolant. For example, one or more of the coolants may comprise a brine,a fluorocarbon liquid, a liquid metal, or other similar coolant, or arefrigerant, while still maintaining the advantages and unique featuresof the present invention.

As noted briefly above, power levels in computer equipment (primarilyprocessors) are rising to a level to where they no longer can simply beair cooled. These components will likely be water cooled. Heatdissipated by the processor can be transferred to water via a watercooled cold plate, certain embodiments of which are described in theabove-incorporated, co-pending United States patent application entitled“Cooling System and Method Employing a Closed Loop Coolant Path andMicro-Scaled Cooling Structure within an Electronics Subsystem of anElectronics Rack”. Further, power produced by leakage current withinelectronics components is now of the same order as the switching powerfor the components, and is a strong function of temperature; that is,the lower the temperature, the lower the leakage current/power.

Generally stated, provided herein is a very high thermal performancecooled electronics module, such as a multichip module. High performancemicro-scaled cooling structures or cold plates are beginning to exist inthe industry, but are geared for single-chip operation. Disclosed hereinare various aspects by which these high performance cold plates areindividually mounted or attached to multiple electronics componentswithin an electronics module. Further, an enclosure with a commonmanifold is provided for distributing coolant in parallel to theindividual cold plates. Methods of assembly and disassembly are alsodescribed, which facilitate an electronics component rework capability.

Referring to the drawings, wherein the same reference numbers usedthrough multiple figures designate the same or similar elements, FIG. 1Adepicts one embodiment of a cooled electronics module, generally denoted100, in accordance with an aspect of the present invention. This moduleincludes a substrate 110, which may include conductive wiring (notshown) on an upper surface thereof and/or embedded therein. One or moreelectronics components 120 are electrically connected to the electricalwiring of substrate 110 via, for example, solder ball connections 121.Multiple discrete cold plates 130 each have a first surface 131configured to couple to the surface to be cooled of a respectiveelectronics component 120. Various techniques can be employed to coupleeach cold plate to its respective electronics component. For example,each discrete cold plate can be fabricated of copper and attached to itsrespective electronics component by a thermally conductive adhesive orvia a suitable solder, such as an indium or an indium-based alloysolder. An example of a suitable thermally conductive adhesive isAblebond 965-1L, manufactured by Ablestik Laboratories, RanchoDominguez, Calif., while indium solder can be obtained from the IndiumCorporation of America, Utica, N.Y. A soldered interface is advantageousin providing a lower thermal resistance, and facilitates reworking ofelectronics components. In alternate embodiments, one or more of thecold plates could comprise a composite metal structure, or a ceramicmaterial if a thermally conductive adhesive is employed as the coldplate-to-electronics component interface.

FIG. 2 depicts one embodiment of a cold plate 130, useful in a coolingapparatus in accordance with the present invention. In this embodiment,cold plate 130 is a coolant-cooled cold plate configured with a coolantinlet 131 and a coolant outlet 132 with at least one coolant chamber 133disposed between the coolant inlet and the coolant outlet. Various othercold plate embodiments may also be employed, including, for example, jetorifice cold plates and cold plates having multiple parallel channelsbetween the coolant inlet and the coolant outlet. Further, as notedabove, each cold plate may comprise a micro-scaled cooling structure,with a characteristic dimension of 200 microns or less.

Returning to FIG. 1A, a plurality of coolant-carrying tubes 140 extendfrom cold plates 130 and couple cold plates 130 in fluid communicationwith an inlet plenum 162 and an outlet plenum 164 of an enclosurecomprising a cap 150 and a manifold 160. As shown, at least twocoolant-carrying tubes 140 extend from a second surface 132 of each coldplate 130. The coolant-carrying tubes 140 are, in one embodiment,identical cylindrical tubes having a common geometric cross-section,e.g., circular, square, rectangular, etc. In the embodiment shown, tubes140 project normal to second surface 132 of the associated cold plate130, and may be formed integral with the associated cold plate or sealedthereto. Alternatively, coolant-carrying tubes 140 may be of two or morediffering cross-sections, in either or both geometry and size. Forexample, both tubes extending from a cold plate may be cylindrical, butone tube may be larger in flow cross-sectional area, or one tube may becylindrical and the other tube square, or elliptical in cross-section.As a further example, one tube may be cylindrical and smaller incross-sectional area, while the other tube may be elliptical and largerin cross-sectional area.

Cap 150 is configured with a plurality of bores (or openings) 151, witheach bore being sized and located to at least partially receive arespective coolant-carrying tube 140 extending from a cold plate 130aligned beneath the bore. Each tube 140 is sealed to an inner wall ofcap 150 defining the respective bore 151 by a sealant, which in thisembodiment, comprises a double O-ring or equivalent elastomeric seal 152disposed between the tube and the cap 150. To facilitate positioning ofthe O-rings, multiple circumferential grooves 154 are provided in theouter surface portion of each tube 140 disposed within the associatedbore. Although shown as a double O-ring for reliability, the sealantcould alternatively be a single O-ring if desired. The purpose of thesealant is to isolate the coolant from directly contacting theelectronics components and their interconnect wiring.

FIG. 1B is a cross-sectional plan view of the electronics module 100 ofFIG. 1A taken along line 1B-1B through manifold 160 of the enclosure. Inthis embodiment, a single inlet plenum 162 and a single outlet plenum164 are provided within manifold 160. A single coolant inlet 163 feedscoolant to inlet plenum 162, while a single coolant outlet 165 exhaustscoolant from outlet plenum 164. Each plenum 162, 164 includes aplurality of fingers or coolant distribution passages which extend overeach coolant-carrying cold plate 130. The fingers of each plenum exposea central flow passage of each tube, with a first set of tubes 161 shownin fluid communication with inlet plenum 162, and a second set of tubes167 in fluid communication with outlet plenum 164. Note that in thisembodiment, each exposed tube 161, 167 is shown to comprise anidentically-sized coolant flow passage. In alternate embodiments, thecoolant-carrying tubes could be differently sized (and/or shaped) tofacilitate the delivery of different amounts of coolant to differentcold plates with different coolant flow characteristics within theelectronics module. A further variation of this concept is depicted inFIGS. 4A & 4B, and described below.

In the embodiment of FIGS. 1A & 1B, cap 150 can be fabricated of anysuitably strong metal or plastic. Manifold 160 can either bemetallurgically, mechanically or chemically attached to cap 150,depending on the choice of cap material, and the type of seal desiredbetween the cap and the manifold. For example, if the cap were to bemade of copper or aluminum, the manifold could be brazed to the capemploying a copper-to-copper braze or an aluminum-to-aluminum braze.Further, the cooling apparatus includes an enclosure, comprising cap 150and manifold 160, which has a perimeter region that engages substrate110 to form an at least partially enclosed cavity 157, with the multipleheat generating electronics components 120 and the multiple cold plates130 disposed within cavity 157. Thus, the cooling apparatus andelectronics assembly together define a cooled electronics module.

FIG. 3 depicts an alternative embodiment of a cooled electronics module300 having the same or similar components to those described above inconnection with the electronics module of FIGS. 1A & 1B. A substrate 110again supports multiple heat generating electronics components 120, eachof which has coupled thereto a cold plate 130. Extending from eachdiscrete cold plate 130 are at least two tubes 140, each in fluidcommunication with one of the inlet plenum 162 and outlet plenum 164configured in the enclosure comprising cap 150 and manifold 160. Again,cap 150 has a perimeter region for engaging substrate 110 to form an atleast partially enclosed cavity 157 within which the multipleelectronics components 120 and multiple cold plates 130 are disposed. Inthis embodiment, cap 150 is again configured with a plurality of bores151, each of which is sized and located to at least partially receive arespective coolant-carrying tube 140 extending from aligned cold plate130. In this alternate embodiment, each tube 140 is sealed to the innerwall of the associated bore 151 via a soldered annular seal 305 disposedbetween the outer surface of each tube and the inner wall of cap 150defining bore 151. Beveling at an upper portion of each bore 151facilitates positioning of solder 305 between each tube 140 and therespective inner wall of cap 150. In this embodiment, cap 150 mightcomprise copper, as would tubes 140. Further, as with the embodiment ofFIGS. 1A & 1B, cold plates 130 may be attached to the respectiveelectronics components 120 via an appropriate thermally conductiveadhesive, or a metallurgical joint.

As referenced above, FIGS. 4A & 4B depict a further embodiment of anelectronics module 400 in accordance with an aspect of the presentinvention. Similar to the above-referenced embodiments, module 400includes a substrate 110, which supports multiple heat generatingelectronics components 120, each of which has coupled thereto a coldplate 130. Extending from each discrete cold plate 130 are at least twotubes 140, each in fluid communication with one of the inlet plenum 162and outlet plenum 164 configured in the enclosure comprising cap 150 andmanifold 160. Again, cap 150 has a perimeter region for engagingsubstrate 110 to form an at least partially enclosed cavity 157 withinwhich the multiple electronics components 120 and multiple cold plates130 are disposed. In this embodiment, cap 150 is configured with aplurality of bores 151, each of which is sized and located to at leastpartially receive a respective coolant-carrying tube 140 extending froman aligned cold plate 130. Each tube 140 is sealed to an inner wall ofcap 150 defining the respective bore 151 by a sealant, which in thisembodiment, comprises a double O-ring or equivalent elastomeric seal 152disposed between the tube and the cap 150. To facilitate positioning ofthe O-rings, multiple circumferential grooves 154 are provided in theouter surface portion of each tube 140 disposed within the associatedbore. Further, as with the embodiment of FIGS. 1A & 1B, cold plates 130may be attached to the respective electronics components 120 viaappropriate thermally conductive adhesive, or a metallurgical joint.

As shown in FIG. 4A, electronics module 400 further includes an orificeplate 405 disposed between cap 150 and manifold 160. This orifice plateis a customized flow plate that allows for the tailoring of coolant flowthrough the individual cold plates 130. As shown, plate 405 isconfigured with different sized openings which align with differentcoolant-carrying tubes 140, thereby tailoring the flow through the tubeseither from inlet plenum 162 or to outlet plenum 164. In the embodimentsof FIGS. 4A & 4B, an opening 410 is provided in orifice plate 405, whichaligns between inlet plenum 162 and a first, leftmost coolant-carryingtube 140, while a second opening 412 is provided in orifice plate 405 toalign between outlet plenum 164 and a second coolant-carrying tube 140.As shown in FIG. 4B, openings 410 & 412 are similarly sized. In themiddle of the module, a smaller opening 420 is provided in orifice plate405 between inlet plenum 162 and a tube 140 in communication with theinlet of the center cold plate 130, while a slightly larger opening 422is aligned between outlet plenum 164 and tube 140 in fluid communicationwith the coolant outlet of this cold plate. By differently sizing theopenings, the pressure drop and the flow rate of fluid through the coldplate can also be controlled, in addition to the amount of fluid in thecold plate. Orifice plate 405 further includes an opening 430 alignedbetween inlet plenum 162 and a corresponding tube 140 coupled in fluidcommunication with the coolant inlet for the rightmost cold plate 130,and an opening 432 aligned between outlet plenum 164 and a second tube140 in fluid communication with the coolant outlet of the rightmost coldplate 130. Although of equal size, these openings are shown to be ofsmaller size than the openings 410 & 412 for the leftmost cold plateillustrated in FIG. 4A (see FIG. 4B). Advantageously, employing anorifice plate to tailor the coolant flow through the multiple coldplates allows for a single sized coolant carrying tube to be employedthroughout the module, while still allowing for tailoring of the coolingachieved by each cold plate, which would be advantageous should the heatgenerating capacity of the electronics components differ when inoperation.

Also shown in FIG. 4A are multiple springs 450, each disposed between arespective cold plate 130 and cap 150. If the interface between coldplates 130 and electronics components 120 is a compliant thermalinterface (e.g., a paste, grease, oil or gel interface), a biasingmechanism, such as springs 450, may be used to provide a desired forceagainst the cold plates to ensure a favorable thermal contact betweeneach cold plate and its respective electronics component, as well asprovide cold plate compliance which allows the electronics components tovary in height and/or orientation within the electronics assembly.

Various methods of fabrication of an electronics module and/or coolingapparatus such as described above can be employed. The particularfabrication or assembly approach depends upon, in one embodiment, thetype of tube-to-cap seal to be employed. If O-ring seals similar to thatdepicted in FIGS. 1A & 1B or 4A & 4B are employed, and the O-rings canwithstand the cold plate-to-electronics component interfacereflow/curing temperature, then the tubes affixed to the cold plate arepartially inserted into the cap, and the cap assembly is brought downonto the substrate to cause the cold plates to contact the electronicscomponents. This intermediate assembly is then taken through theappropriate temperature cycle to make the cold plate-to-electronicscomponent joint. Springs can be added between the cold plates and thecap to ensure good contact at the cold plate-electronics componentinterface. Alternatively, if the manifold is already in place above thecap, the manifold could be pressurized using air or an inert gas.Pressurizing the manifold region results in a net force on the coldplates that will cause the cold plates to be in compression with theelectronics components, thus assuring a properly formed low thermalinterface joint. If the O-ring seal cannot withstand the desired joiningtemperature, then a separate fixture can be used to position and jointhe cold plates to the electronics components without the O-ringspresent. The O-rings would then be added to the coolant-carrying tubes,and finally the cap or cap/manifold assembly would be placed onto thesubstrate.

If the solder seal version of FIG. 3 is to be employed, then assemblydepends on the reflow temperature of the tube-to-cap joint/seal. If thereflow temperature of this seal is less than that for the coldplate-electronics component joint, then the cold plates would be joinedto the electronics components first using the proper fixturing, and thenthe cold plate tubes would be joined to the cap in a second operation.Note that it is assumed in this discussion that the coolant-carryingtubes are affixed to or integral with the cold plates. If the tube-capjoint reflow temperature is higher than that of the coldplate-electronics component joint, then the cap-cold plate-modulesubassembly can be reflowed in one step.

Electronics module disassembly for component rework is also possible.For an O-ring seal version such as depicted in FIGS. 1A & 1B or 4A & 4B,the cap and manifold subassembly can be removed, leaving the cold plateson the electronics components, with the cold plates then being removedfrom the electronics components prior to component rework. For thesoldered seal version of FIG. 3, if the tube-cap joint reflowtemperature is less than the joining temperature at the coldplate-electronics component interface, then a reflow and cap/manifoldremoval can be performed first, followed by the cold plate removalemploying the different reflow temperatures. If the tube-cap jointreflow temperature is higher than that of the cold plate-electronicscomponent interface, then only one reflow step is required to remove thecooling apparatus from the electronics assembly.

Although preferred embodiments have been depicted and described indetail herein, it will be apparent to those skilled in the relevant artthat various modifications, additions, substitutions and the like can bemade without departing from the spirit of the invention and these aretherefore considered to be within the scope of the invention as definedin the following claims.

1. A cooling apparatus for an electronics assembly comprising asubstrate supporting multiple heat generating electronics components,the cooling apparatus comprising: multiple discrete cold plates, eachcold plate having a first surface configured to couple to a respectiveelectronics component of the multiple electronics components, and eachcold plate being a coolant-cooled cold plate including a coolant inletand a coolant outlet with at least one coolant chamber disposed betweenthe coolant inlet and the coolant outlet; a plurality ofcoolant-carrying tubes, each cold plate having at least twocoolant-carrying tubes of the plurality of coolant-carrying tubesextending from a second surface thereof, each coolant-carrying tubebeing in fluid communication with one of the coolant inlet and thecoolant outlet of the cold plate from which the coolant-carrying tubeextends; an enclosure having a perimeter region for engaging thesubstrate to form an at least partially enclosed cavity with themultiple heat generating electronics components and the multiple coldplates being disposed within the cavity defined by the substrate and theenclosure, and wherein the enclosure is configured with a plurality ofbores, each bore being sized and located to at least partially receive arespective coolant-carrying tube of the plurality of coolant-carryingtubes extending from the cold plates, the enclosure further beingconfigured with a manifold in fluid communication with the plurality ofbores and the plurality of coolant-carrying tubes disposed therein fordistributing coolant in parallel to at least some cold plates of themultiple cold plates via a first set of coolant-carrying tubes of theplurality of coolant-carrying tubes in fluid communication with thecoolant inlets of the multiple cold plates, and for receiving coolantfrom at least some cold plates of the multiple cold plates via a secondset of coolant-carrying tubes of the plurality of coolant-carrying tubesin fluid communication with the coolant outlets of the multiple coldplates; and wherein the manifold further comprises a coolant inletplenum and a coolant outlet plenum, the first set of coolant-carryingtubes being in fluid communication with the coolant inlet plenum andcoupling in parallel the coolant inlets of the cold plates to thecoolant inlet plenum, and the second set of coolant-carrying tubes beingin fluid communication with the coolant outlet plenum and coupling inparallel the coolant outlets of the cold plates to the coolant outletplenum, and the coolant inlet plenum and the coolant outlet plenum eachcomprising a plurality of coolant distribution fingers which extend overthe at least some cold plates of the multiple cold plates forfacilitating distribution of coolant in parallel to the at least somecold plates.
 2. The cooling apparatus of claim 1, wherein the enclosurefurther comprises a cap, the cap being configured with the plurality ofbores sized and located to at least partially receive thecoolant-carrying tubes extending from the cold plates, and beingdisposed between the manifold and the cold plates, and wherein theplurality of coolant distribution fingers of the coolant inlet plenumare interdigitated with the plurality of coolant distribution fingers ofthe coolant outlet plenum.
 3. The cooling apparatus of claim 2, whereinthe manifold is configured with a single inlet opening in fluidcommunication with the coolant inlet plenum and a single outlet openingin fluid communication with the coolant outlet plenum, the single inletopening allowing coolant to be fed to the coolant inlet plenum, and thesingle outlet opening allowing coolant to be exhausted from the coolantoutlet plenum.
 4. The cooling apparatus of claim 2, wherein theenclosure further comprises an orifice plate disposed between the capand the manifold, the orifice plate being configured with a plurality oforifices, and wherein each coolant-carrying tube is axially aligned withan orifice of the plurality of orifices of the orifice plate, andcoolant flows through each aligned orifice and coolant-carrying tubewhen passing between the enclosure and the multiple cold plates.
 5. Thecooling apparatus of claim 4, wherein at least some orifices of theplurality of orifices in the orifice plate are differently sizedresulting in different amounts of coolant flow through the multiple coldplates, and wherein the different sizes of the at least some orificesare tailored so that coolant flow through the multiple cold platesresults in a desired operating temperature for each electronicscomponent, and wherein at least some electronics components of themultiple electronics components generate different amounts of heat whenin operation.
 6. The cooling apparatus of claim 2, further comprising asealant disposed between each coolant-carrying tube and an inner wall ofthe cap defining the associated bore at least partially receiving thecoolant-carrying tube, and wherein the sealant comprises at least one ofsolder or at least one O-ring seal.
 7. The cooling apparatus of claim 6,further comprising an interface material disposed between the firstsurface of each cold plate and its respective electronics component, theinterface material comprising at least one of an adhesive or ametallurgical bond.
 8. The cooling apparatus of claim 6, furthercomprising multiple spring biasing mechanisms, each spring biasingmechanism being coupled to a respective cold plate and being disposedbetween the cap and the respective cold plate, each biasing mechanismbiasing the respective cold plate away from the cap, and towards theassociated heat generating electronics component when the coolingapparatus is in use.
 9. The cooling apparatus of claim 6, wherein thesealant comprises two O-ring seals, and wherein each coolant-carryingtube has two circumferential grooves in an outer surface portion thereofdisposed within the associated bore, each circumferential groovepartially receiving and positioning one O-ring seal of the two O-ringseals.
 10. The cooling apparatus of claim 1, wherein the plurality ofcoolant-carrying tubes are similarly configured and sized, and whereinthe bores in the enclosure are sufficiently sized to accommodate atleast one of height and angular orientation variation of at least someelectronics components relative to the substrate.
 11. A cooledelectronics module comprising: an electronics assembly including asubstrate and multiple heat generating electronics components; and acooling apparatus for facilitating cooling of the multiple heatgenerating electronics components, the cooling apparatus comprising:multiple discrete cold plates, each cold plate having a first surfaceconfigured to couple to a respective electronics component of themultiple electronics components, and each cold plate being acoolant-cooled cold plate configured with a coolant inlet and a coolantoutlet with at least one coolant chamber disposed between the coolantinlet and the coolant outlet; a plurality of coolant-carrying tubes,each cold plate having at least two coolant-carrying tubes of theplurality of coolant-carrying tubes extending from a second surfacethereof, each coolant-carrying tube being in fluid communication withone of the coolant inlet and the coolant outlet of the cold plate fromwhich the coolant-carrying tube extends; and an enclosure having aperimeter region engaging the substrate to form an at least partiallyenclosed cavity with the multiple heat generating electronics componentsand the multiple cold plates being disposed within the cavity defined bythe substrate and the enclosure, and wherein the enclosure is configuredwith a plurality of bores, each bore being sized and located to at leastpartially receive a respective coolant-carrying tube of the plurality ofcoolant-carrying tubes extending from the cold plates, the enclosurefurther being configured with a manifold in fluid communication with theplurality of bores and the plurality of coolant-carrying tubes disposedtherein for distributing coolant in parallel to at least some coldplates of the multiple cold plates via a first set of coolant-carryingtubes of the plurality of coolant-carrying tubes in fluid communicationwith the coolant inlets of the multiple cold plates, and for receivingcoolant from at least some cold plates of the multiple cold plates via asecond set of coolant-carrying tubes of the plurality ofcoolant-carrying tubes in fluid communication with the coolant outletsof the multiple cold plates.
 12. The cooled electronics module of claim11, wherein the enclosure further comprises a cap, the cap beingconfigured with the plurality of bores sized and located to at leastpartially receive the coolant-carrying tubes extending from the coldplates, and being disposed between the manifold and the cold plates, andwherein the plurality of coolant distribution fingers of the coolantinlet plenum are interdigitated with the plurality of coolantdistribution fingers of the coolant outlet plenum.
 13. The cooledelectronics module of claim 12, wherein the enclosure further comprisesan orifice plate disposed between the cap and the manifold, the orificeplate being configured with a plurality of orifices, and wherein eachcoolant-carrying tube is axially aligned with an orifice of theplurality of orifices of the orifice plate, and coolant flows througheach aligned orifice and coolant-carrying tube when passing between theenclosure and the multiple cold plates.
 14. The cooled electronicsmodule of claim 13, wherein at least some orifices of the plurality oforifices in the orifice plate are differently sized resulting indifferent amounts of coolant flow through the multiple cold plates, andwherein the different sizes of the at least some orifices are tailoredso that coolant flow through the multiple cold plates results in adesired operating temperature for each electronics component, andwherein at least some electronics components of the multiple electronicscomponents generate different amounts of heat when in operation.
 15. Thecooled electronics module of claim 12, further comprising a sealantdisposed between each coolant-carrying tube and an inner wall of the capdefining the associated bore at least partially receiving thecoolant-carrying tube, and wherein the sealant comprises at least one ofsolder or at least one O-ring seal, and further comprising an interfacematerial disposed between the first surface of each cold plate and itsrespective electronics component, the interface material comprising atleast one of an adhesive or a metallurgical bond.
 16. The cooledelectronics module of claim 15, wherein the sealant comprises two O-ringseals, and wherein each coolant-carrying tube as two circumferentialgrooves in an outer surface portion thereof disposed within theassociated bore, each circumferential groove partially receiving andpositioning one O-ring seal of the two O-ring seals.
 17. The cooledelectronics module of claim 11, wherein the plurality ofcoolant-carrying tubes are similarly configured and sized, and whereinthe bores in the enclosure are sufficiently sized to accommodate atleast one of height and angular orientation variation of at least someelectronics components relative to the substrate.